Inorg. Chem. 1992, 31, 3083-3090
3083
Synthesis by Ligand Exchange, Structural Characterization, and Aqueous Chemistry of Ortho-Palladated Oximes Alexander D. Ryabov,*J' Gregory M. Kazankov,lbAnatoly K. Yatsimirsky,lbLudmila G. Kuz'mina,lc Ol'ga Yu. Burtseva,le Natalia V. Dvortsova,lc and Vladimir A. PolyakovId Division of Chemistry, G. V. Plekhanov Russian Economic Academy, Stremyanny per. 28, 113054, Moscow, Russia, Department of Chemistry, Moscow State University, 119899, Moscow, Russia, N. S. Kurnakov Institute of General and Inorganic Chemistry, Leninsky pr. 31, 117907, Moscow, Russia, and Mendeleev Institute of Chemical Technology, Miusskaya pl. 9, 125190, Moscow, Russia
Received January 29, 1992 Dimeric chloro-bridgedortho-palladated complexes of general formula [P~CI(C~H~(CR=NOH)-~)]Z, where R = H, Me, Et, and Ph, were prepared via the ligand-exchangereaction starting from aryl oximes and cyclopalladated complexes of N,N-dimethylbenzylamine, ((dimethylamino)methyl)ferrocene,or benzophenone oxime. By reaction with various pyridines (Zpy), the dimers were converted into the corresponding monomers [PdCl(C6H4(CR=NOH)Z)(Zpy)] (4). Four acetophenone oxime (R = Me) derivatives with Z = H (4b),4-MezN (4c),2-Me (a), and 2,4,6-Me3 (4e) were characterized by X-ray crystallography. Compound 4b: C13H13N20PdCl,orthorhombic, space group Pcab, a = 15.385 (4) A, b = 20.980 (1) A, c = 8.140 (1) A, Z = 8. Compound 4c: C15HlsN30PdC1, triclinic, space group Pi,a = 8.307 (5) A, b = 8.772 (6) A, c = 11.949 (8) A, a = 82.15 (5)O, 0 = 77.36 (5)O, y = 68.00 (5)O, Z = 2. Compound 4d: C ~ ~ H I S N Z ~ P ~ C ~monoclinic, . ~ / Z C ~ space H ~ , group C 2 / c , a = 21.978 (8) A, b = 9.702 (2) A, c = 21.728 (8) A, @ = 132.99 (2)O, Z = 8. Compound 4e: C16H19N20PdCll monoclinic, space groupP21/n, a = 9.488 (2) A, b = 15.664 (4) A, c = 11.221 (3) A, 0 = 91.12 (1)O, Z = 4. All have a square planar coordination at palladium with a slight tetrahedral distortion and trans nitrogens. The pyridine and palladium planes are practically perpendicular only in the case of 4 , e ; an interaction of the pyridine 2- and 2,6-methyl C-H bonds with the palladium axial sites is proposed. The Pd-Cl bond length is large in all four complexes, of ca. 2.4 A, and the chloro ligand is readily hydrolyzed in aqueous solution to afford the aqua/hydroxo species [Pd(C6H4(CR=NOH)-2)(Zpy)OHn](n--')+ (n = 1, 2). In the pH range 3-9 the complexes are involved in two acid-base equilibria with the values of pK,l and pK,z of ca. 7 and
